public override void read()
{
//if (_port == null) return ;
//SerialPort port = new SerialPort(this.InterfaceName, this.parameter);
//port.Open();
//var factory = new ModbusFactory();
//IModbusMaster master = factory.CreateRtuMaster(port);
// read back
ushort[] rb = new ushort[2];
rb[0] = ReadAddress;
rb[1] = 2;
ReadCommand?.Invoke(this, rb);
}